Dear All,
I posted the following message to the ISOGG list in response to
Katherine Borges' call for DNA success stories and so I thought I would post
it here as well to help illustrate how autosomal DNA data can help a
genealogist confirm theories about genealogical connections. Hopefully,
stories like this will become increasingly common.
Sincerely,
Tim Janzen

Dear Katherine,
I have a success story for you. For over 30 years I have been trying to
establish the ancestry of my great great great grandfather Jacob Youngman
(b. ca Aug 1823, d. 24 May 1903). No one in our family knew his ancestry,
but his son Charles Youngman (b. 1872) left a tantilizing clue in his
biography that was published in the book "History of Harrison County,
Missouri" where Charles Youngman says that Jacob Youngman's father lived in
Kentucky, moved to Indiana where he entered land, and later moved to central
Missouri where he died. Not too many Youngmans fit this discription. In
the past 6 months I have been focussing on a John Youngman who is listed in
the 1840 Census in Clay County, Missouri, but is not listed there in the
1850 Census. A William Youngman (b. ca 1818) appears in nearby Ray County,
Missouri in the 1850 Census, so I assumed that John Youngman must have died
between 1840 and 1850. This past fall I learned that John Youngman didn't
die prior to 1850, but instead moved to Denton County, Texas where he is
listed in the 1850 Census with his family. Meanwhile, my ancestor Jacob
Youngman is listed in Shelby Co., Indiana in the 1850 Census. This
genealogical puzzle is complicated by the fact that John Youngman appears to
have been married 3 times and was divorced from his first two wives. He had
children by all three wives with Jacob Youngman seeming to be his son by his
second wife Elizabeth Reeves. This past fall I was able to establish
contact with another Youngman researcher, Susie Brewer, whose husband is a
great great grandson of Mary Jane Youngman (b. Nov 1835), who appears to be
a half-sister to Jacob Youngman (b. ca Aug 1823), being a daughter of John
Youngman's third wife Priscilla Clark. The key evidence to solving this
genealogical puzzle has come from autosomal DNA testing. Susie Brewer was
recently able to get a DNA sample from Gene Brewer's first cousin once
removed Troy McCoy. Troy is a great grandson of Mary Jane Youngman. Troy's
23andMe DNA results when compared to the results of descendents of Jacob
Youngman helped nail down the relationship fairly conclusively in my
opinion.
Troy McCoy has at least the following highly significant matching
segments with my Youngman relatives:
1. a 10 cM matching segment as well as 4.5, 4.2, and 4.1 cM matching
segments with my mother's 2nd cousin Jennifer Burklund
2. a 23.6 cM matching segment with my mom's first cousin Mason Youngman
3. a 16 cM matching segment and a 9.3 cM matching segment with my mother's
first cousin Judy Wigton
4. a 12 cM matching segment with my mothers 3rd cousin Frederick Mock
5. a 11 cM matching segment and a 4.9 cM matching segment with my mother's
brother Lawrence Youngman
6. a 15.8 cM matching segment and a 5.6 cM matching segment with my
mother's brother Robert Youngman
7. a 11 cM matching segment with my mother Betty (Youngman) Janzen

The proper way to analyze this data is create an average for the 7
relatives in my family. It is reasonable to assume that all of the matching
segments over 5 cMs in length came from a shared common ancestor. The sum
of the centimorgans for the 7 Youngman siblings or cousins included is 114.3
and the average is 16.3. This average is supportive of my theory that Troy
McCoys great grandmother Mary Jane Youngman (b. ca 1836) was a 1/2 sibling
to my mother's great great grandfather Jacob Youngman (b. ca Aug 1823). If
Mary Jane Youngman and Jacob Youngman were full siblings this would make
Troy McCoy a 3rd cousin once removed to my mom. If Mary Jane Youngman and
Jacob Youngman were half-siblings this would make Troy McCoy a ½ 3rd cousin
once removed to my mom. We know that 3rd cousins once removed should share
.391% of their DNA in common and that that ½ 3rd cousin once removed should
share .195% of their DNA in common. There are about 7200 cM of DNA in the
entire genome. Thus we would expect that on average ½ 3rd cousins once
removed would share about 14 cMs of DNA in common with each other. We are
seeing slightly above that for the comparison between Troy McCoy and my
close Youngman relatives. Thus, I think that it is safe to say that the DNA
data suggests that Mary Jane Youngman and Jacob Youngman were half-siblings.